Compounds having analgesic and/or immunostimulant activity

ABSTRACT

The compounds shown by their structural formulas in the specification have analgesic and or immunostimulant activity in mammals.

CLAIM OF PRIORITY

This is a national stage application under 35 U.S.C. §371 of PCTapplication PCT/US2006/002580, filed on Jan. 25, 2006, which claims thebenefit of Provisional Application No. 60/647,271, filed on Jan. 26,2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to compounds having analgesic and in somecases immunostimulant activity.

The present invention also relates to pharmaceutical compositionscontaining these compounds as active ingredient for alleviating oreliminating pain in mammals and/or stimulating the immune system inmammals and to methods of using said pharmaceutical compositions asanalgesics and or immunostimulants.

2. Background Art

Several compounds falling within one or more of the general definitionsas “derivatives of 3-aryl-3-hydroxy-2-amino-propionic acid amides, of3-heteroaryl-3-hydroxy-2-amino-propionic acid amides, of1-aryl-1-hydroxy-2,3-diamino-propyl amines,1-heteroaryl-1-hydroxy-2,3-diamino-propyl amines” are known in thepatent and scientific literature.

For example, United States Patent Application Publications US2003/0153768; US 2003/0050299 disclose several examples of theabove-mentioned known compounds. The N-acyl compounds of thesereferences are said to be useful as N-acylsphingosineglucosyltransferase inhibitors, the amide and the reduced compounds aredescribed as intermediates in their preparations.

Illustrative specific examples of compounds of these references areshown below:

The publication Shin et al. Tetrahedron Asymmetry, 2000, 11, 3293-3301discloses the following compounds:

L-threo-PDMP and some other known compounds used in the methods of thisinvention are commercially available, in pure enantiomeric and racemicforms, as applicable, from Matreya, LLC Pleasant Gap, Pa.

U.S. Pat. Nos. 5,945,442; 5,952,370; 6,030,995 and 6,051,598, which areall related to each other as being based on same or related disclosures,describe compounds which are structurally similar to the known compoundsshown above. The compounds of these U.S. patent references are said tobe inhibitors of the enzyme glucosylceramide (GlcCer) syntethase.

A publication in Journal of Labelled Compounds & Radiopharmaceuticals(1996), 38(3), 285-97 discloses the compound of the formula

Published PCT application WO 01/38228 discloses

in connection with a chromatographic method.

Kastron et al. in Latvijas PSR Zinatnu Akademijas Vestis, Kimijas Serija(1965) (4), 474-7 disclose the following compound.

Significantly, according to the best knowledge of the present inventorsnone of the above shown prior art compounds are disclosed in the priorart to have analgesics or immunostimulants activity.

SUMMARY OF THE INVENTION

The present invention is directed to novel compounds shown by theirstructural formulas below:

where R₄ is H, alkyl of 1 to 6 carbons or CO—R₅ where R₅ is alkyl of 1to 6 carbons;

where R₄ is H, alkyl of 1 to 6 carbons or CO—R₅ where R₅ is alkyl of 1to 6 carbons;

where R₄ is H, alkyl of 1 to 6 carbons or CO—R₅ where R₅ is alkyl of 1to 6 carbons;

where R₄ is H, alkyl of 1 to 6 carbons or CO—R₅ where R₅ is alkyl of 1to 6 carbons;

where R₄ is H, alkyl of 1 to 6 carbons or CO—R₅ where R₅ is alkyl of 1to 6 carbons, andto all pharmaceutically acceptable salts of said compounds.

The present invention is also directed to pharmaceutical compositionscontaining the above-noted novel compound to be used as analgesicsand/or immunostimulants in mammals and to methods of using saidpharmaceutical compositions as analgesics and/or as immunostimulants.

DETAILED DESCRIPTION OF THE INVENTION

A general description of the compounds of the invention is provided inthe Summary Section of the present application for patent. Severalcompounds of the invention contain one or more asymmetric centers, suchthat the compounds may exist in enantiomeric as well as indiastereomeric forms. In fact, most of the compounds of the presentinvention have two asymmetric carbons adjacent to one another andtherefore can exist in erythro or threo form, with each of these twoforms having dextrorotatory (D) or levorotary (L) enantiomers. Althoughthe threo form is generally preferred in accordance with the presentinvention for analgesic activity, unless it is specifically notedotherwise, the scope of the present invention includes all enantiomers,diastereomers and diastereomeric and racemic mixtures. In light of theforegoing, it should be clearly understood that the designation “DL” or“(+/−)” or “(±)” in this application includes the pure dextrorotatoryenantiomer, the pure levorotatory enantiomer and all racemic mixtures,including mixtures where the two enantiomers are present in equal or inunequal proportions. Moreover, for simplicity sake in many of thestructural formulas, such as in the example below, only one of theenantiomers is actually shown but when the designation “DL” (or “(+/−)”or “(±)”) appears it also includes the enantiomeric form (mirror image)of the structure actually shown in the formula.

For Example:

Thus, in the example above, only one enantiomer is shown, but becausethe designation “DL” (or “(+/−)” or “(±)”) appears below the formula,its optical isomer

and all racemic mixtures of the two optical isomers are also included.

In the case of some compounds of the present invention one enantiomer ofthe threo, and in some cases of the erythro, is significantly moreactive as an analgesic or immunostimulant than the other enantiomer ofthe same pair. For this reason the isolated enantiomer which issignificantly more active than the other is considered a novel andinventive composition even if the racemic mixture or one singleenantiomer of the same compounds have already been described in theprior art.

Some of the novel compounds of the present invention may contain threeor more asymmetric centers.

Keeping the foregoing examples in mind a person of ordinary skill in theart should readily understand the scope of each described example,although in a broad sense all isomers, enantiomers and racemic mixturesare within the scope of the invention.

The term “alkyl” in the general description and definition of thecompounds includes straight chain as well as branch-chained alkylgroups.

Generally speaking the compounds of the invention may form salts withpharmaceutically acceptable acids or bases, and such pharmaceuticallyacceptable salts of the compounds are also within the scope of theinvention.

Referring now to the novel compounds of the invention the R₄ group shownabove and in the claims, is preferably H.

The presently most preferred novel compounds of the invention aredisclosed with their structural formulas in the ensuing Table and ordescription, showing activity of exemplary compounds relevant to theirability to act as analgesics.

Biological Activity, Modes of Administration

The novel compounds of the invention have analgesic and/orimmunostimulant activity in mammals. Some of the compounds described inthe introductory section which per se are known in the art have beendiscovered by the present inventors to also have analgesic effect inmammals. To the best of the knowledge of the present inventors theanalgesic or immunostimulant biological activity of the known compoundswas not known before the present discovery.

An art-accepted model or assay for measuring an analgesic effect of acompound in chronic pain (in particular peripheral neuropathy) is themodel known as Kim and Chung 1992, Pain 150, pp 355-363 (Chung model).This model involves the surgical ligation of the L5 (and optionally theL6) spinal nerves on one side in experimental animals. Rats recoveringfrom the surgery gain weight and display a level of general activitysimilar to that of normal rats. However, these rats developabnormalities of the foot, wherein the hindpaw is moderately everted andthe toes are held together. More importantly, the hindpaw on the sideaffected by the surgery appears to become sensitive to low-thresholdmechanical stimuli and will perceive pain instead of the faint sensationof touch. This sensitivity to normally non-painful touch, called“tactile allodynia”, develops within the first week after surgery andlasts for at least two months. The allodynia response includes liftingthe affected hindpaw to escape from the stimulus, licking the paw andholding it in the air for many seconds. None of these responses isnormally seen in the control group.

To produce the tactile allodynia, rats are anesthetized before surgery.The surgical site is shaved and prepared either with betadine orNovacaine. Incision is made from the thoracic vertebra X111 down towardthe sacrum. Muscle tissue is separated from the spinal vertebra (leftside) at the L4-S2 levels. The L6 vertebra is located and the transverseprocess is carefully removed with a small rongeur to expose the L4-L6spinal nerves. The L5 and L6 spinal nerves are isolated and tightlyligated with 6-0 silk thread. The same procedure is done on the rightside as a control, except no ligation of the spinal nerves is performed.

After a complete hemostasis is confirmed, the wounds are sutured. Asmall amount of antibiotic ointment is applied to the incised area, andthe rat is transferred to the recovery plastic cage under a regulatedheat-temperature lamp.

On the day of the experiment, at least seven days after the surgery,typically six rats per test group are administered the test drugs byintraperitoneal (i.p.) injection or oral gavage (p.o.). For i.p.administration, the compounds are formulated in H₂O and given in avolume of 1 ml/kg body weight by injecting into the intraperitonealcavity. For p.o. administration, the compounds are formulated in H₂O andgiven in a volume of 1 ml/kg body weight using an 18-gauge, 3 inchgavage needle that is slowly inserted through the esophagus into thestomach.

Tactile allodynia is assessed via von Frey hairs, which are a series offine hairs with incremental differences in stiffness. Rats are placed ina plastic cage with a wire mesh bottom and allowed to acclimate forapproximately 30 minutes. To establish the pre-drug baseline, the vonFrey hairs are applied perpendicularly through the mesh to themid-plantar region of the rats' hindpaw with sufficient force to causeslight buckling and held for 6-8 seconds. The applied force has beencalculated to range from 0.41 to 15.1 grams. If the paw is sharplywithdrawn, it is considered a positive response. A normal animal willnot respond to stimuli in this range, but a surgically ligated paw willbe withdrawn in response to a 1-2 gram hair. The 50% paw withdrawalthreshold is determined using the method of Dixon, W. J., Ann. Rev.Pharmacol. Toxicol. 20:441-462 (1980) hereby incorporated by reference.Tactile allodynia is measured prior to and 15, 30, and 60 minutes afterdrug administration. The post-drug threshold is compared to the pre-drugthreshold and the percent reversal of tactile sensitivity is calculatedbased on a normal threshold of 15.1 grams.

Table 1 below indicates the degree of pain reversal obtained in theChung model with exemplary compounds of the invention. Theintraperitonial (i.p.) and/or intravenous (iv) administration of thecompounds was in doses ranging from 1 μg/kg to 300 μg/kg or 3 mg/kg POand the peak percentage of reversal of allodynia was measured at 15, 30or 60 minutes after administration, as is indicated in the table. Dataare expressed as the highest % allodynia reversal (out of 3 time points:15 min, 30 min, or 60 min. post-drug) with a minimum of a 20% allodyniareversal in the rat Chung model. Comparisons between groups (drugtreated vs. saline treated) were made using a two-tailed, 2-sample,unpaired t-test. Compounds that are not shown which were notstatistically analgesic following an IP dose of 300 ug/kg, but may stillbe analgesic. Compounds that do not exhibit significant analgesia at 100mg/kg are not considered to be analgesic.

TABLE 1 Peak % Dose Pain μg/kg Reversal: Mode Compound time post of Admi# Chemical Formula dose Nistr. 19

 43% 30 min 300 μg/kg IP 50

100% 60 min 300 μg/ kg PO

threo 70

 69% 60 min 300 μg/kg IP (+/−) 49

 85% 60 min 100 μg/kg IP 300

 53% 60 min 300 μg/kg IP

An art accepted method for measuring immunostimulation comprisessystemic administration of compounds to assay for the ability tostimulate the immune system, possibly due to nonspecific upregulation ofthe hemolymphoreticular system. This upregulation could result inincreased numbers of lymphocytes of both T- and B-cell lineage. Althoughapplicant does not wish to be bound by the biological theory of theimmunostimulation, actual immunostimulatory efficacy of the compoundscan be demonstrated in vivo by assaying splenic size in response toadministration of the test compound to laboratory test species rats.Thus, increase in spleen size demonstrates immunostimulatory potentialof the compound. Generally speaking any compound that exhibits splenicenlargement following dosing of 200 mg/kg or less may be considered animmunostimulant.

Modes of Administration:

The compounds of the invention may be administered at pharmaceuticallyeffective dosages. Such dosages are normally the minimum dose necessaryto achieve the desired therapeutic effect; in the treatment of chromicpain, this amount would be roughly that necessary to reduce thediscomfort caused by the pain to tolerable levels. For human adults suchdoses generally will be in the range 0.1-5000 mg/day; more preferably inthe range 1 to 3000 mg/day, still more preferably in the range of 10 mgto 1000 mg/day. However, the actual amount of the compound to beadministered in any given case will be determined by a physician takinginto account the relevant circumstances, such as the severity of thepain, the age and weight of the patient, the patient's general physicalcondition, the cause of the pain, and the route of administration.

The compounds are useful in the treatment of pain in a mammal;particularly a human being. Preferably, the patient will be given thecompound orally in any acceptable form, such as a tablet, liquid,capsule, powder and the like. However, other routes may be desirable ornecessary, particularly if the patient suffers from nausea. Such otherroutes may include, without exception, transdermal, intraperitonial,parenteral, subcutaneous, intranasal, intrathecal, intramuscular,intravenous and intrarectal modes of delivery. Another aspect of theinvention is drawn to therapeutic compositions comprising the novelcompounds of the invention and pharmaceutically acceptable salts ofthese compounds and a pharmaceutically acceptable excipient. Such anexcipient may be a carrier or a diluent; this is usually mixed with theactive compound, or permitted to dilute or enclose the active compound.If a diluent, the carrier may be solid, semi-solid, or liquid materialthat acts as an excipient or vehicle for the active compound. Theformulations may also include wetting agents, emulsifying agents,preserving agents, sweetening agents, and/or flavoring agents. If usedas in an ophthalmic or infusion format, the formulation will usuallycontain one or more salt to influence the osmotic pressure of theformulation.

In another aspect, the invention is directed to methods for thetreatment of pain, particularly chronic pain, through the administrationof one or more of the novel or otherwise known compounds of theinvention, or of pharmaceutically acceptable salts thereof to a mammalin need thereof. As indicated above, the compound will usually beformulated in a form consistent with the desired mode of delivery.

Compounds of the invention which are immunostimulants are administeredsubject to the same basic principles as the compounds having analgesicactivity, in doses which are best determined on a case-by-case and/orspecies-by-species and, in case of humans, at times on apatient-by-patient basis. Generally speaking the effective dose will bein the range of 10 μg/kg to 200 mg/kg.

Synthetic Methods for Obtaining the Compounds of the Invention

The compound of the invention can be synthesized by utilizing thesynthetic methods described in the experimental below, or suchmodifications of the below described experimental methods which willbecome readily apparent to those skilled in the art in light of thepresent disclosure. More specifically, the synthesis of each compound ofthe invention is described for the specific compounds wherein thevariable R₄ is H. It will be readily understood by those skilled in theart that the compounds wherein the variable R₄ is alkyl of 1 to 6carbons or CO—R₅ where R₅ is alkyl of 1 to 6 carbons can be readily madeby processes well known in the art, such as alkylation or acylation,respectively. It will also be readily understood by those skilled in theart that for the performance of the alkylation or acylation of thehydroxyl group other groups, such as the amino group, may need to beprotected and the protective group can be subsequently removed byprocesses well known in the art. In some cases the alkylation oracylation of the hydroxyl group may be performed on an intermediate inthe synthetic process leading to the compounds of the invention.

General

¹H NMR spectra were recorded at ambient temperature with an Avance 300(Bruker) spectrometer. The compounds were analyzed by reverse phase highperformance liquid chromatography (HPLC) using a Waters AutopurificationSystem equipped with a Waters 2525 Pump, a Waters 2696 photodiode arraydetector, and a XTerra column (Part. No. 186000482, 5 μm, C18, 4.5×50mm).

The HPLC method used was a gradient of 5% solvent B to 100% in 7 min.Solvent A was H₂O with 0.05% TFA and solvent B was CH₃CN with 0.05% TFA(Method A).

Melting points were measured with a Büchi B-545 melting point apparatusand were uncorrected. To isolate reaction products the solvent wereremoved by evaporation using a vacuum rotatory evaporator, the waterbath temperature not exceeding 40° C.

General Synthetic Routes

The compound of the invention can be synthesized by utilizing thesynthetic methods described in a general sense immediately below and inmore detail in the experimental section of the present application, orby such modifications of the below described general and experimentalmethods which will become readily apparent to those skilled in the artin light of the present disclosure.

DETAILED DESCRIPTION OF THE SYNTHESIS OF PREFERRED COMPOUNDSExperimental

Preparation of Compound 19.

2-Isocyano-1-(pyrrolidin-1-yl)ethanone BLE 04098.

To stirred and cooled (0° C.) methyl isocyanoacetate (96% technicalgrade, 5.0 g, 47.8 mmol) was slowly added in 0.75 h pyrrolidine (6.5 mL,78 mmol). The mixture was stirred for 1.5 h with continued cooling andthen concentrated. The resulting oil was co-evaporated twice fromCH₂Cl₂:hexane to remove residual pyrrolidine.2-Isocyano-1-(pyrrolidin-1-yl)ethanone BLE 04098 was obtained as ayellow solid (6.85 g, 98% yield) and used in the next step withoutpurification.

MW: 138.17; Yield: 98%; yellow solid; Mp (° C.)=73.9.

¹H-NMR (CDCl₃, *): 1.81-2.08 (m, 4H, 2×CH₂), 3.35-3.45 (m, 2H, N—CH₂),3.50-3.60 (m, 2H, N—CH₂), 4.23 (s, 2H, CH₂CO).

General Method B: Exemplified by the preparation oftrans-(4,5-dihydro-5-(pyridin-3-yl)oxazol-4-yl)(pyrrolidin-1-yl)methanoneBLE 04110B.

To a stirred and cooled (0° C.) solution of potassium hydroxide (0.55 g,9.80 mmol) in methanol (10 mL) were added a mixture of 3-pyridinecarboxaldehyde (1.03 mL, 10.84 mmol) and2-isocyano-1-(pyrrolidin-1-yl)ethanone BLE 04098 (1.50 g, 10.86 mmol).The solution was stirred 3 h at 0° C. and then concentrated. The residuewas partitioned between ethyl acetate (100 mL) and water. The organiclayer was combined with two additional ethyl acetate extracts (2×100mL), washed with aqueous sodium chloride and dried over MgSO₄, filteredand evaporated. Concentration afforded a crude product which waspurified by column chromatography on silica (CH₂Cl₂:MeOH=98:2) to yieldtotrans-(4,5-dihydro-5-(pyridin-3-yl)oxazol-4-yl)(pyrrolidin-1-yl)methanoneBLE 04110B (0.95 g, 39%) as a pale yellow pale solid.

MW: 245.28; Yield: 39%; Yellow Pale Solid; Mp (° C.): 107.0.

¹H-NMR (CDCl₃, *): 1.78-2.10 (m, 4H, 2×CH₂), 3.40-3.61 (m, 3H, CH₂N),3.90-4.04 (m, 1H, CH₂N), 4.59 (dd, 1H, J=7.7 Hz, J=2.2 Hz, CH—N), 6.21(d, 1H, J=7.7 Hz, CH—O), 7.04 (d, 1H, J=2.2 Hz, O—CH═N), 7.33 (m, 1H,ArH), 7.64 (m, 1H, ArH), 8.59 (d, 2H, J=2.8 Hz, ArH).

¹³C-NMR (CDCl₃, *): 24.2, 26.0, 46.4, 46.6, 75.7, 79.3, 123.7, 133.5,135.3, 147.6, 149.9, 155.2, 166.2.

trans-(4,5-Dihydro-5-(pyridin-4-yl)oxazol-4-yl)(pyrrolidin-1-yl)methanoneCompound 19.

Compound 19 was prepared in accordance with method B usingpyridine-4-carbaldehyde (1.88 mL, 19.76 mmol), KOH (1.01 g, 18.00 mmol)in methanol (18 mL) and 2-isocyano-1-(pyrrolidin-1-yl)ethanone BLE 04098(2.73 g, 19.76 mmol). The residue was partitioned between ethyl acetate(200 mL) and water (150 mL). The organic layer was combined withadditional ethyl acetate extracts (2×150 mL), washed with aqueous sodiumchloride (2×150 mL) and dried over MgSO₄, filtered and evaporated.Trans-(4,5-dihydro-5-(pyridin-4-yl)oxazol-4-yl)(pyrrolidin-1-yl)methanoneCompound 19 was obtained as a white solid (4.32 g, 98% yield).

MW: 245.28; Yield: 98%; White Solid; Mp (° C.)=69.2.

R_(f): 0.65 (MeOH:CH₂Cl₂=10:90).

¹H-NMR (CDCl₃, *): 1.78-2.06 (m, 4H, 2×CH₂), 3.44-3.60 (m, 3H, CH₂N),3.90-4.01 (m, 1H, CH₂N), 4.52 (dd, 1H, J=7.9 Hz, J=2.2 Hz, CH—N), 6.19(d, J=7.9 Hz, 1H, CH—O), 7.03 (d, 1H, J=2.2 Hz, N═CH—O), 7.24 (dd, 2H,J=4.5 Hz, J=1.5 Hz, ArH), 8.61 (dd, 2H, J=4.5 Hz, J=1.5 Hz, ArH).

Preparation of Compound 50.

General Method C: Exemplified by the preparation ofDL-threo-2-amino-3-hydroxy-3-(pyridin-3-yl)-1-(pyrrolidin-1-yl)propan-1-onedihydrochloride Compound 20.

To a solution oftrans-(4,5-dihydro-5-(pyridin-3-yl)oxazol-4-yl)(pyrrolidin-1-yl)methanoneBLE 04110B (0.932 g, 3.80 mmol) in MeOH (10 mL) was added hydrochloricacid 37% (1.2 mL). After heating (50° C.) the mixture for 2.25 h thereaction mixture was concentrated and the crude product was coevaporatedtwice with ethyl acetate. After trituration with ethyl acetate,filtration and dryingDL-threo-2-amino-3-hydroxy-3-(pyridin-3-yl)-1-(pyrrolidin-1-yl)propan-1-onedihydrochloride Compound 20 was obtained as a white solid (1.10 g, 94%yield).

MW: 308.2; Yield: 94%; White Solid; Mp (° C.): 123.4.

¹H-NMR (CD₃OD, *): 1.65-2.00 (m, 4H, 2×CH₂), 2.82-3.11 (m, 1H, —CH₂N),3.30-3.57 (m, 2H, C₂HN), 3.57-3.77 (m, 1H, CH₂N), 4.54 (d, 1H, J=5.3 Hz,CH—N), 5.38 (d, 1H, J=5.3 Hz, CH—O), 8.15 (dd, 1H, J=7.6 Hz, J=5.0 Hz,ArH), 8.68 (d, 1H, J=7.6 Hz, ArH), 8.89 (d, 1H, J=7.6 Hz, ArH), 8.96 (s,1H, ArH).

¹³C-NMR (CD₃OD, *): 24.9, 26.9, 47.7, 48.2, 58.1, 69.6, 128.7, 141.5,141.6, 143.1, 146.5, 165.4.

DL-threo-2-Amino-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1-onedihydrochloride Compound 22.

Compound 22 was prepared following method C withtrans-(4,5-dihydro-5-(pyridin-4-yl)oxazol-4-yl)(pyrrolidin-1-yl)methanoneCompound 19 (0.750 g, 3.07 mmol), hydrochloric acid 37% (1.0 mL) andmethanol (10 mL). After 3.0 h at 50° C. and work-upDL-threo-2-amino-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1-onedihydrochloride Compound 22 was obtained as a white solid (0.935 g, 99%yield).

MW: 308.28; Yield: 99%; White Solid; Mp (° C.): 117.0.

¹H-NMR (CD₃OD, *): 1.75-2.03 (m, 4H, 2×CH₂), 2.93-3.08 (m, 1H, CH—N),3.32-3.75 (m, 3H, 2×CH₂), 4.54 (d, 1H, J=5.9 Hz, CH—N), 5.40 (d, 1H,J=5.9 Hz, CH—O), 8.21 (d, 2H, J=5.8 Hz, ArH), 8.94 (d, 2H, J=5.8 Hz,ArH).

MS-ESI m/z (% rel. int.): 236.1 ([MH]⁺, 17), 219 (25), 148 (100).

HPLC: Method A, detection UV 254 nm, Compound 22 RT=0.8 min, peak area96.3%.

tert-Butyl5-(DL-threo-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-ylcarbamoyl)pentylcarbamateEBE 06102.

To a suspension ofDL-threo-2-amino-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1-onedihydrochloride Compound 22 (0.60 g, 1.77 mmol) in CH₂Cl₂ (12 mL) wasadded TEA (0.739 mL, 5.32 mmol) and the reaction mixture was stirred for10 min and cooled in an ice bath with continuous stirring. A solution ofBoc-aminohexanoic acid (0.451 g, 1.951 mmol) and BOP (1.05 g, 1.95 mmol)was pre-prepared in CH₂Cl₂ and added dropwise for 5 min. The reactionmixture was stirred for 2 h at 0° C. and 16 h at RT. After evaporationof the volatiles, the residue was dissolved in EtOAc, washed withNaH₂PO₄ pH 7.2, saturated NaHCO₃, dried over Na₂SO₄. The resulting whitesolid was purified by column chromatography on silica gel with 10% EtOAcin EtOAc to give tert-butyl5-(DL-threo-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-ylcarbamoyl)pentylcarbamateEBE 06102 (0.41 g, 52% yield) as a white solid.

MW: 448.56; Yield: 52.0%; White Solid.

R_(f): 0.10 (EtOAc:MeOH=90:10).

¹H-NMR: (CDCl₃, *): 1.10-1.12 (m, 2H, CH₂), 1.35-1.55 (m, 11H, (CH₃)₃ &CH₂), 1.72-1.92 (m, 4H, CH₂), 2.05-2.22 (m, 2H, CH₂), 2.40 (d, 2H, J=9.3Hz, CH₂), 3.05 (q, 2H, J=6.6 Hz, CH₂), 3.20-3.28 (m, 1H, NCH₂),3.32-3.50 (m, 2H, NCH₂), 3.62-3.72 (m, 1H, NCH₂), 4.79 (bs, 1H, NH),4.97 (dd, 1H, J=8.7, 4.1 Hz, NCH), 5.07 (d, 1H, J=4.1 Hz, OCH), 5.40(bs, 1H, NH), 6.74 (d, 1H, J=8.4 Hz, OH), 7.35 (d, 2H, J=6.0 Hz, ArH),8.56 (d, 2H, J=6.0 Hz, ArH).

¹³C-NMR (CDCl₃, *): 24.0, 25.0, 26.1, 28.4, 29.6, 35.9, 36.9, 40.3,46.1, 46.9, 54.9, 72.9, 79.0, 121.3, 148.8, 149.6, 156.1, 169.0, 173.2.

MS-ESI m/z (% rel. Int.): 449.1 ([MH]⁺, 20).

HPLC: Method A, detection UV 254 nm, EBE 06102 RT=4.1 min, peak area99.9%.

6-(5-((3aR,6S,6aS)-hexahydro-2-oxo-1H-thieno[3,4-d]imidazol-6-yl)pentanamido)-N-((1R,2S)-&(1S,2R)-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-yl)hexanamidesCompound 50.

To a solution of5-(DL-threo-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-ylcarbamoyl)pentylcarbamateEBE 06102 (0.370 g, 0.824 mmol), in MeOH (1 mL) was added a solution ofHCl (4.2 M) in EtOAc (10 mL). The reaction mixture was stirred for 2 hat RT and the volatiles were evaporated to yield a crude brown oil EBE06104 (0.221 g, 63% crude yield) that was used without purification inthe next step. To a suspension of EBE 06104 (0.221 g, 0.522 mmol) inCH₂Cl₂ (5 mL) was added triethylamine (0.217 mL, 1.57 mmol) and thereaction mixture was stirred for 10 min and cooled in an ice bath withcontinuous stirring. A solution of biotin (0.14 g, 0.574 mmol) and BOP(0.309 g, 0.574 mmol) was pre-prepared in CH₂Cl₂ (1 mL) and addeddropwise for 5 min. The mixture was stirred for 2 h at 0° C. and 16 h atRT. The reaction mixture was evaporated to dryness, partitioned betweenNaH₂PO₄ and n-Butanol. The n-butanol phase was washed with saturatedNa₂CO₃ and evaporated to dryness. The desired product was isolated usingcolumn chromatography (EtOAc:MeOH:NH₄OH=70:28:2) to give Compound 50(diastereoisomeric mixture in ratio 1:1, 0.160 g, 53% yield) as a whitesolid.

MW: 574.74; Yield: 53%; White Solid; Mp (° C.): 64.3.

R_(f): 0.2 (EtOAc:MeOH:NH₄OH=70:28:2).

¹H-NMR (CDCl₃, *): 1.17-1.32 (m, 2H), 1.40-1.60 (m, 4H), 1.60-1.90 (m,6H), 1.90-2.10 (m, 4H), 2.15-2.30 (m, 4H), 2.74 (d, 1H, J=12.6 Hz), 2.91(dd, J=4.8 Hz, 12.8 Hz), 2.95-3.10 (m, 1H), 3.10-3.45 (m, 4H), 3.60-3.72(m, 1H), 4.34 (dd, 1H J=4.4 Hz J=7.5 Hz), 4.50-4.58 (m, 1H), 4.85-4.95(m, 1H), 5.02-5.08 (m, 1H), 6.12 (s, 1H), 6.50-6.15 (m, 1H), 6.68 (s,1H), 7.36 (m, 2H), 7.67 (q, 1H, J=8.12 Hz), 8.55 (d, 2H, J=5.8 Hz).

MS-ESI m/z (% rel. Int.): 575.3 ([MH]⁺, 70).

HPLC: Method A, detection UV 254 nm, Compound 50 RT=3.61 min, peak area97.2%.

Preparation of Compound 49.

trans-(4,5-Dihydro-5-(2-methoxypyridin-3-yl)oxazol-4-yl)(pyrrolidin-1-yl)methanoneBAL 01014.

BAL 01014 was prepared in accordance with method D using2-methoxy-3-pyridinecarboxaldehyde (0.64 ml, 5.43 mmol), KOH (0.305 mg,5.43 mmol) in methanol (5 mL) and 2-isocyano-1-(pyrrolidin-1-yl)ethanoneBLE 04098 (0.75 g, 5.43 mmol). After work-uptrans-(4,5-dihydro-5-(2-methoxypyridin-3-yl)oxazol-4-yl)(pyrrolidin-1-yl)methanoneBAL 01014 was obtained (0.74 mg, 50% yield) as a white solid.

MW: 275.30; Yield: 50%; White Solid; Mp (° C.): 110.1.

Rf: 0.25 (EtOAc).

¹H NMR (CDCl₃, *): 1.82-2.10 (m, 4H, 2×CH₂), 3.40-3.62 (m, 3 H, CH₂N),3.80-3.90 (m, 3 H, CH₂N), 3.93 (s, 3H, OMe), 4.61 (dd, 1H, J=7 Hz, J=2Hz, CH—N), 6.14 (d, 1H, J=7 Hz, CH—O), 6.90 (dd, 1H, J=7.3 Hz, J=5 Hz,ArH), 7.02 (d, 1H, J=2 Hz, OCH═N), 7.60 (dd, 1H, J=7.3 Hz, J=1.7 Hz,ArH), 8.13 (dd, 1H, J=5 Hz, J=1.8 Hz, ArH).

¹³C-NMR (CDCl₃, *): 24.3, 26.1, 46.3, 46.6, 53.5, 73.5, 78.1, 116.8,122.2, 135.2, 146.5, 155.3, 160.5 and 167.4.

MS-ESI m/z (% rel. Int.): 276.1 ([MH]⁺, 42).

HPLC: Method A, detection UV 254 nm, BAL 01014 RT=3.63 min, peak area97.2%.

3-(DL-threo-2-Amino-1-hydroxy-3-oxo-3-pyrrolidin-1-yl-propyl)-1H-pyridin-2-onehydrochloride Compound 49.

trans-(4,5-Dihydro-5-(2-methoxypyridin-3-yl)oxazol-4-yl)(pyrrolidin-1-yl)methanoneBAL 01014 (0.684 g, 2.487 mmol) was dissolved in methanol (10 mL). Asolution of hydrochloric acid (37%, 0.6 mL) was added via syringe at RT.The mixture was stirred for 22 h at reflux. The residue wasconcentrated, triturated with EtOAc and filtered to obtain a yellow palesolid3-(DL-threo-2-amino-1-hydroxy-3-oxo-3-pyrrolidin-1-yl-propyl)-1H-pyridin-2-onehydrochloride Compound 49 (136 mg, 19.0% yield).

MW: 287.74; Yield: 19.0%; Yellow Pale Solid; Mp (° C.): 180.

¹H NMR (CD₃OD, *): 1.82-2.09 (m, 4H, CH₂), 3.35-3.80 (m, 4 H, CH₂N),4.63 (s, 1H, CH—N), 5.17 (s, 1H, CH—O), 6.56 (t, 1H, ArH)), 7.5 (d, 1H,J=6.1 Hz, ArH), 7.86 (d, 1H, J=6.5 Hz, ArH).

¹³C-NMR (CD₃OD, *): 24.2, 26.0, 46.6, 46.6, 75.8, 79.7, 127.3, 127.5,127.9, 129.4, 130.0, 132.3, 133.2, 148.1, 148.4, 155.3, 166.2.

MS-ESI m/z (% rel. Int.): 252.1 ([MH]⁺, 18), 163.0 (100).

HPLC: Method A, detection UV 254 nm, Compound 49 RT=1.13 min, peak area84.0%.

Preparation of Compound 300.

(±)-threo-2-Phthalimide-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1-onehydrochloride Compound 300.

(±)-threo-2-Amino-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1-onedihydrochloride Compound 22 (0.51 g, 1.64 mmol) was treated by 20 mL ofa 1 N aqueous solution of K₂CO₃ and extracted (5×40 mL) with a mixtureCH₂Cl₂:MeOH=90:10. The solution was dried over MgSO₄, filtered andevaporated to obtain the free base of Compound 22 (0.323 g, 82.5% yield)as a white solid.

In a 10 mL round-bottom flask phtalic anhydride (0.203 mg, 1.373 mmol)was added to the free base of Compound 22 (0.323 g, 1.37 mmol) and themixture was heated from 65° C. to 145° C. and stirred 5 min at 145° C.After cooling a yellow black gum was obtained as a crude product. Thiscrude product was purified by column chromatography (SiO₂,EtOAc:MeOH=100:0 to 90:10). After evaporation of the solvents, a whitesolid(±)-threo-2-phthalimide-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1-oneBLE 04156A was obtained as a white solid (0.15 g, 30% yield). To(±)-threo-2-phthalimide-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1-oneBLE 04156A (0.135 g, 0.37 mmol) was added a solution 0.1 N of HCl inisopropanol (10 mL) and the mixture was evaporated to dryness at 28° C.on a rotavapor then to high vacuum pump.(±)-threo-2-Phthalimide-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1-onehydrochloride Compound 300 (0.147 g, 24.5% yield) was obtained as awhite solid.

MW: 401.84; Yield: 24.5%; White Solid; Mp (° C.): 201.8

¹H-NMR (CD₃OD, *): 1.60-1.90 (m, 4H, 2×CH₂), 2.95-3.09 (m, 1H, CH₂N),3.30-3.47 (m, 3H, CH₂N), 5.30 (d, 1H, J=7.9 Hz, CH), 5.82 (d, 1H, J=7.9Hz, CH), 7.80 (m, 4H, ArH), 8.25 (d, 2H, J=5.4 Hz, ArH), 8.81 (d, 2H,J=5.2 Hz, ArH).

¹³C-NMR (CD₃OD, *): 24.7, 27.1, 47.7, 47.8, 58.0, 70.6, 124.8 (2×C),127.5 (2×C), 132.6 (2×C), 136.1 (2×C), 142.5 (2×C), 164.9, 166.5, 168.8.

MS-ESI m/z (% rel. Int.): 366.0 ([MH]⁺, 22), 219.1 (100), 148.0 (47).

HPLC: Method A, detection UV 254 nm, RT=3.88 min, peak area 98.7%.

Preparation of Compound 301.

tert-butyl5-(±)-threo-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-ylcarbamoyl)pentylcarbamateCompound 237.

To a solution of N-Boc-aminohexanoic acid (342 mg, 1.48 mmol) in THF (10mL) was added N-methylmorpholine (163 μL, 1.48 mmol). The solution wasstirred for 5 min, cooled at −15° C. and treated dropwise with isobutylchloroformate (211 μL, 1.48 mmol). This solution was added via astainless steal cannula to a solution of(±)-threo-2-amino-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1-onedihydrochloride Compound 22 (500 mg, 1.48 mmol) and N-methyl-morpholine(489 mg, 1.47 mmol) in THF (10 mL) at −15° C. The reaction mixture waskept for 0.5 h at −15° C. followed by 2 h at 25° C. with continuousstirring. After evaporation of the solvent, the residue was partitionedbetween EtOAc and H₂O, washed with NaH₂PO₄, saturated aqueous NaHCO₃,dried over sodium sulfate and purified by column chromatography (SiO₂)with a gradient of 0% to 10% [v/v] MeOH in EtOAc to give tert-butyl5-((±)-threo-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-ylcarbamoyl)pentylcarbamateCompound 237 (455 mg, 69% yield) as a white solid.

MW: 448.6; Yield: 69%; White Solid.

R_(f): 0.20 (EtOAc:MeOH=90:10).

¹H-NMR (CD₃OD, 6): 1.05-1.15 (m, 2H, CH₂), 1.35-1.55 (m, 13H,2×CH₂+C(CH₃)₃), 1.75-1.95 (m, 4H, 2×CH₂), 2.00-2.20 (m, 2H, O═CCH₂),3.05 (q, 2H, J=6.7 Hz, N—CH₂), 3.20-3.35 (m, 1H, N—CH), 3.38-3.50 (m,2H, N—CH₂), 3.65-3.75 (m, 1H, N—CH), 4.72 (bs, 1H, NH), 4.98 (dd, 1H,J=8.8 Hz, J=3.6 Hz), 5.08 (d, 1H, J=3.3 Hz, OCH), 5.23 (bs, 1H, OH),6.50 (d, 1H, J=8.7 Hz, NH), 7.35 (d, 2H, J=6.0 Hz, ArH), 8.58 (d, 2H,J=4.6 Hz, J=1.4 Hz, ArH).

MS-ESI m/z (% rel. Int.): 449.2 ([MH]⁺, 30), 349.2 (100).

HPLC: Method A, detection at 254 nm, RT=4.03 min, peak area 99.9%.

6-Amino-N-((±)-threo-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-yl)hexanamideCompound 238.

To a solution of tert-butyl5-((±)-threo-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-ylcarbamoyl)pentylcarbamateCompound 237 (81 mg, 0.181 mmol) in CH₂Cl₂ (8 mL) was added TFA (2 mL)at 0° C. and stirred for 2 h at 0° C. All the volatiles were evaporatedto give a residue that was treated with a suspension of Amberlite-400(OH⁻) in MeOH. After filtration, the filtrate was evaporated and theproduct was isolated by column chromatography (SiO₂) withCH₂Cl₂:MeOH:NH₄OH=10:5:0.4 to afford6-amino-N-((±)-threo-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-yl)hexanamideCompound 238 (40 mg, 64% yield) as a white solid.

MW: 448.6; Yield: 64%; White Solid; Mp (° C.): 134.4

R_(f): 0.30 (CH₂Cl₂:MeOH:NH₄OH=10:5:0.4).

¹H NMR (CDCl₃, δ): 1.12-1.30 (m, 2H, CH₂), 1.30-1.50 (m, 2H, CH₂),1.50-1.65 (m, 2H, CH₂), 1.65-1.95 (m, 4H, CH₂), 2.10-2.30 (m, 2H, CH₂),2.55-2.70 (t, 2H, J=6.9 Hz, CH₂), 3.10-3.20 (m, 2H, CH₂), 3.28-3.50 (m,2H, CH₂), 3.60-3.70 (m, 1H, CH), 4.95 (dd, 1H, J=5.1 Hz, J=8.4 Hz,O—CH), 5.02 (d, 1H, J=5.0 Hz, OH), 7.11 Hz (d, J=8.48 Hz, 1H, ArH), 7.35(dd, 2H, J=4.4 Hz, J=1.5 Hz, ArH), 8.55 (dd, J=1.5 Hz, J=4.6 Hz, 2H,ArH).

¹³C NMR (CDCl₃, δ): 24.0, 25.1, 25.8, 25.9, 32.5, 35.8, 41.7, 46.0,46.9, 55.6, 72.6, 121.3 (2×C), 149.2, 149.5 (2×C), 168.9, 173.7.

(±)-threo-{3-[3-(3-{5-[1-(Hydroxy-pyridin-4-yl-methyl)-2-oxo-2-pyrrolidin-1-yl-ethylcarbamoyl]-pentylcarbamoyl}-propylcarbamoyl)-propylcarbamoyl]-propyl}-carbamicacid tert-butyl ester TTA 08156.

Boc-GABA-GABA-GABA-OH (354 mg, 0.95 mmol) was stirred in CHCl₃ (40 mL)with Et₃N (0.3 mL, 2.1 mmol) and HOBT (145 mg, 1.05 mmol) at 4° C. for 5min under nitrogen. EDC (205 mg, 1.05 mmol) was added and the mixturewas stirred for 15 min at 4° C.6-Amino-N-((±)-threo-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-yl)hexanamide(333 mg, 0.95 mmol) in CHCl₃ (20 mL) was added dropwise and the mixturewas stirred at 4° C. for 2 h and 15 h at RT under nitrogen. Brine (30mL) was added and the product was extracted by CH₂Cl₂ (200 mL). Theorganic layer was washed with a solution of 2 N NaOH, brine and driedover MgSO₄. After filtration the solution was evaporated and dried togive a crude yellow oil (420 mg). After purification by columnchromatography (SiO₂, CH₂Cl₂:MeOH=85:15)(±)-threo-{3-[3-(3-{5-[1-(hydroxy-pyridin-4-yl-methyl)-2-oxo-2-pyrrolidin-1-yl-ethylcarbamoyl]-pentylcarbamoyl}-propylcarbamoyl)-propylcarbamoyl]-propyl}-carbamicacid tert-butyl ester TTA 08156 (260 mg, 39% yield) was obtained as apale yellow oil.

MW: 703.87; Yield: 39%; Pale Yellow Oil.

R_(f): 0.20 (CH₂Cl₂:MeOH=9:1).

¹H-NMR (CDCl₃, δ): 1.17-1.25 (m, 2H, CH₂), 1.40-1.56 (m, 13H, 2×CH₂,3×CH₃) 1.73-1.85 (m, 10H, 5×CH₂), 2.13-2.29 (m, 8H, 4×CH₂CO), 2.40 (s,1H, OH), 3.09-3.67 (m, 12H, 6×CH₂—N), 4.91 (dd, 1H, J=4.9 Hz, J=8.5 Hz,CH—N), 5.05 (d, 1H, J=5.1 Hz, CH—O), 5.15 (t, 1H, J=5.8 Hz, NH),7.01-7.04 (m, 1H, NH), 7.14 (t, 1H, J=5.6 Hz, NH), 7.33 (t, 1H, J=5.6Hz, NH), 7.37 (d, 2H, J=6.0 Hz, ArH), 8.55 (d, 2H, J=6.0 Hz, ArH).

¹³C-NMR (CD₃OD, 6): 24.0, 24.9, 25.6, 25.8, 26.1, 26.5, 28.4 (3×C),29.0, 33.5, 33.7, 35.8, 38.6, 38.8, 39.1, 39.6, 46.1, 46.8, 55.6, 72.7,79.5, 121.5 (×2), 149.1, 149.5 (×2), 156.7, 168.8, 173.1, 173.3, 173.4,173.5.

MS-ESI m/z (% rel. Int.): 704.3 ([MH]⁺, 100).

HPLC: Method A, detection UV 254 nm, TTA 08156 RT=3.90 min, peak area99.0%.

6-(5-((3aR,6S6aS)-hexahydro-2-oxo-1H-thieno[3,4-d]imidazol-6-yl)-pentanoylamino)-butyrylamino-butyrylamino-butyrylamino-N-((1R,2S)-&(1S,2R)-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-yl)hexanamidesCompound 301.

(±)-threo-{3-[3-(3-{5-[1-(Hydroxy-pyridin-4-yl-methyl)-2-oxo-2-pyrrolidin-1-yl-ethylcarbamoyl]-pentylcarbamoyl}-propylcarbamoyl)-propylcarbamoyl]-propyl}-carbamicacid tert-butyl ester TTA 08156 (260 mg, 0.37 mmol) was stirred in MeOH(5 mL) with HCl 37% (0.3 mL, 3.70 mmol) for 15 min at 40° C. MeOH wasevaporated and the residue was dried in vacuum. Amberlite IRA-400 (Cl⁻)(6 mL, 8.4 mmol) was washed successively with water (2×10 mL), NaOH 0.5N (3×20 mL), water (2×10 mL) and MeOH (3×10 mL). The previously obtainedresidue and washed Amberlite were stirred in MeOH (30 mL) for 5 min atRT. After filtration, the MeOH was evaporated to give amine in the freebase form (210 mg, 94% yield). Biotin (95 mg, 0.38 mmole) was dissolvedin a mixture CHCl₃/DMF (40 mL/10 mL) and Et₃N (0.11 mL, 0.77 mmol), HOBT(53 mg, 0.38 mmol) and EDC (75 mg, 0.38 mmol) were added and thesolution stirred at RT for 2 h under nitrogen. The previously obtainedamine (210 mg, 0.35 mmol) in CHCl₃ (10 mL) was added dropwise and themixture was stirred for 24 h at RT under nitrogen. Brine (40 mL), 2 NNaOH (10 mL), CHCl₃ (50 mL) were added and the product was extracted by3 additional extractions of a mixture CHCl₃/DMF (50 mL/10 mL). Thecombined organic layer was washed with brine, dried over MgSO₄,filtered, evaporated to give crude yellow oil (160 mg, 52% yield). Thecrude oil was purified by column chromatography (SiO₂,CH₂Cl₂:MeOH:NH₃=95:5:0.1 to 85:15:0.3) to obtain after evaporation6-(5-((3aR,6S,6aS)-hexahydro-2-oxo-1H-thieno[3,4-d]imidazol-6-yl)-pentanoylamino)-butyrylamino-butyrylamino-butyrylamino-N-((1R,2S)-&(1S,2R)-1-hydroxy-3-oxo-1-(pyridin-4-yl)-3-(pyrrolidin-1-yl)propan-2-yl)hexanamides(diastereoisomeric mixture ratio 1:1) as a pale yellow oil (45 mg, 15%yield).

MW: 830.05; Yield: 15%; Pale Yellow Oil.

R_(f): 0.30 (CH₂Cl₂:MeOH:NH₃=85:15:0.3).

¹H-NMR (CD₃OD, δ): 1.26-1.82 (m, 22H, 11×CH₂), 2.18-2.25 (m, 10H,5×CH₂CO), 2.70 (d, 1H, J=12.7 Hz, CH₂—S), 2.92 (dd, 1H, J=4.8 Hz, J=12.7Hz, CH₂S), 3.06-3.80 (m, 13H, 6×CH₂—N, CH—S), 4.29 (dd, 1H, J=4.4 Hz,J=7.8 Hz, CH—N), 4.48 (dd, 1H, J=4.9 Hz, J=7.8 Hz, CH—N), 4.82 (d, 1H,J=6.4 Hz, CH—N), 5.01 (d, 1H, J=6.4 Hz, CH—O), 7.49 (d, 2H, J=5.5 Hz,ArH), 8.5 (d, 2H, J=4.6 Hz, ArH).

¹³C-NMR (CD₃OD, δ): 25.0, 26.5, 26.8, (2×C), 26.9 (2×C), 27.5, 29.5,29.8, 30.1, 34.3, 34.4 (2×C), 36.4, 36.8, 39.8, 39.9, 40.1, 41.1, 47.2,47.3, 57.1, 58.3, 61.6, 63.4, 73.1, 74.2, 123.5 (2×C), 149.9 (2×C),152.8, 166.1, 170.0, 175.3, 175.4 (2×C), 176.0, 176.1.

MS-ESI m/z (% rel. Int.): 830.2. ([MH]⁺, 85), 219.1 (100).

HPLC: Method A, detection UV 254 nm, RT=3.70 min, peak area 99.8%.

Preparation of Compound 302.

(±)-threo-2-Amino-3-hydroxy-3-(piperidin-4-yl)-1-(pyrrolidin-1-yl)propan-1-onedihydrochloride Compound 302.

(±)-threo-2-Amino-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1-onedihydrochloride Compound 22 (500 mg, 1.61 mmol) was stirred in AcOH (10mL) with PtO₂ hydrate typical (Pt content 79-84%, 100 mg) under hydrogenat atmospheric pressure for 24 h at RT. After filtration on Celite® 545,the filtrate was evaporated and the residue was dried under vacuum togive a beige solid (450 mg, 88.2% yield). The crude product was stirredin MeOH (50 mL) with Amberlite (Cl⁻) IRA-400 (9 mL, 12.7 mmol washedbeforehand by NaOH 0.5 N then water and MeOH) at RT for 15 min. Themixture was filtered off, the filtrate was evaporated and the free baseform was purified by column chromatography (SiO₂, CH₂Cl₂:MeOH:20% NH₃ inH₂O=70:30:8) to give(±)-threo-2-amino-3-hydroxy-3-(piperidin-4-yl)-1-(pyrrolidin-1-yl)propan-1-oneTTA 08144A (226 mg, 58% yield). HCl Treatment in MeOH gave(±)-threo-2-amino-3-hydroxy-3-(piperidin-4-yl)-1-(pyrrolidin-1-yl)propan-1-onedihydrochloride Compound 302 (190 mg, 28% yield) as a white solid.

MW: 314.25; Yield: 28.0%; White Solid; Mp (° C.): 197.5

R_(f): 0.20 (CH₂Cl₂:MeOH:20% NH₃ in H₂O=70:30:8, free base).

¹H-NMR (CD₃OD, δ): 1.57-2.00 (m, 9H, 4×CH₂ & CH), 2.94-3.08 (m, 2H,CH₂—N), 3.46-3.77 (m, 7H, 3×CH₂—N, CH—N), 4.33 (s, 1H, CH—O).

¹³C-NMR (CD₃OD, δ): 22.5, 23.4, 24.1, 24.7, 35.2, 42.2, 42.5, 45.4,45.5, 52.0, 69.8, 164.6.

MS-ESI m/z (% rel. Int.): 242.2 ([MH]⁺, 45), 129.1 (100).

HPLC: Method A, detection UV 214 nm, RT=0.70 min, peak area 98.0%.

Preparation of Compound 70

Method D (in CH₂Cl₂):

To a stirred solution ofDL-threo-2-amino-3-hydroxy-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-1′-onedihydrochloride Compound 22 (0.15 g, 0.49 mmol) in 10 mL of CH₂Cl₂ at+4° C. were added triethylamine (200 μl, 1.45 mmol) and very slowly acidchloride in 3 mL of CH₂Cl₂. The mixture was stirred overnight at RTunder nitrogen and then partitioned between CH₂Cl₂ and 1 N aqueoussodium carbonate. The organic layer was evaporated and the obtainedresidue purified by column chromatography on silica (EtOAc:MeOH=95:5).The hydrochloride salt was obtained in MeOH at 0° C. with 0.3 M HCl indiethylether to give after evaporation of solvents and drying theacylated compound.

BenzylDL-threo-3-hydroxy-1-oxo-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-2-ylcarbamatehydrochloride Compound 58.

The compound was prepared according to method D with benzylchloroformate (91 mg, 0.53 mmol). After work-up benzylDL-threo-3-hydroxy-1-oxo-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-2-ylcarbamatehydrochloride Compound 58 was obtained as a white solid (90 mg, 46%yield).

MW: 405.9; Yield: 46.0%; White Solid; Mp (° C.): 185.3.

R_(f): 0.38 (MeOH:EtOAc=10:90) free base.

¹H-NMR (CD₃OD, *): 1.87-2.03 (m, 4H, 2×CH₂), 3.40-3.48 (m, 2H, CH₂N),3.56-3.62 (m, 2H, CH₂N), 4.85-5.04 (m, 3H, CH₂O, CHO), 5.39 (d, 1H,J=2.8 Hz, NH), 7.26-7.36 (m, 5H, ArH), 8.12 (d, 2H, J=6.0 Hz, ArH), 8.69(d, 2H, J=6.0 Hz, ArH).

¹³C-NMR (CD₃OD, *): 25.0, 27.0, 47.5, 48.0, 58.8, 67.9, 72.7, 126.6(2×C), 129.1, 129.2, 129.5, 138.1, 141.9 (2×C), 158.1, 164.4, 169.2.

MS-ESI m/z (% rel. Int.): 370.1 ([MH]⁺, 15), 219.0 (100).

HPLC: Method A, detection UV 254 nm, Compound 58 RT=4.10 min, peak area99.8%.

trans-3-Methyl-5-pyridin-4-yl-4-(pyrrolidine-1-carbonyl)-oxazolidin-2-onehydrochloride Compound 70.

To a stirred solution ofDL-threo-3-hydroxy-1-oxo-3-(pyridin-4-yl)-1-(pyrrolidin-1-yl)propan-2-ylcarbamateCompound 58 free base (0.10 g, 0.27 mmol) in a mixture of DMSO:DMF (2mL:0.2 mL) at 6° C. were added slowly tert-BuOK (38 mg, 0.33 mmol) anddimethyl sulfate (26 μL, 0.27 mmol). The mixture was stirred 15 h at RTunder nitrogen and partitioned between ice water (5 mL), 1M Na₂CO₃ (2mL) and ethyl acetate (100 mL). The organic phase was washed with brine(20 mL) and dried over MgSO₄. After removing ethyl acetate byevaporation, the crude product was dried to give the crude free base asan oil. The hydrochloride salt was obtained in MeOH at 0° C. using a 0.3M solution of HCl in diethylether. After precipitation in diethylether,trans-3-methyl-5-pyridin-4-yl-4-(pyrrolidine-1-carbonyl)-oxazolidin-2-onehydrochloride was obtained as a pale yellow solid (80 mg, 95% yield). Afurther crystallization in EtOAc:MeOH (10:1) gave Compound 70 as a whitesolid (16 mg, 20% yield).

MW: 311.76; Yield: 20%; White Solid; Mp (° C.): 168.6.

R_(f): 0.15 (EtOAc:MeOH=95:5), free base.

¹H-NMR (CD₃OD, δ): 1.90-2.10 (m, 4H, 2×CH₂), 2.84 (s, 3H, CH₃),3.47-3.70 (m, 4H, CH₂N), 4.82 (m, 1H, CH), 5.89 (m, 1H, CH), 8.17 (m,2H, ArH), 8.97 (m, 2H, ArH).

¹³C-NMR (CD₃OD, δ): 24.9, 27.1, 30.2, 48.1, 64.9, 76.3, 125.6 (2×C),143.8 (2×C), 159.1, 160.1, 167.3.

MS-ESI m/z (% rel. Int.): 276.1 ([MH]⁺, 25), 177.1 (100).

HPLC: Method A, detection UV 254 nm, Compound 70 RT=2.00 min, peak area97.0%.

What is claimed is:
 1. A compound of the formula

where R₄ is H, alkyl of 1 to 6 carbons or CO—R₅ where R₅ is alkyl of 1 to 6 carbons or any other pharmaceutically acceptable salt of said compound.
 2. A compound in accordance with claim 1 where R₄ is H.
 3. A method of treating pain in a mammal in need of such treatment, comprising administering to said mammal the compound in accordance with claim 1 or any other pharmaceutically acceptable salt of said compound.
 4. A pharmaceutical composition comprising the compound of claim 1 or any other pharmaceutically acceptable salt of said compound and a pharmaceutically acceptable excipient. 